Israeli soldiers have shot and killed at least 52 Palestinians and left another 1,200 injured during mass protests along the Gaza border, health officials said.

It was the deadliest day in the region since a devastating 2014 cross-border war, and cast a shadow over the inauguration of the new US embassy in Jerusalem.

In a show of anger fuelled by the embassy move, Palestinian protesters set tyres on fire and hurled firebombs and stones toward Israeli troops across the border. Later, Israeli forces opened fire from tanks, sending protesters fleeing for cover.

The military said its troops came under fire in some areas, and claimed protesters had been attempting to break through the border fence. It said troops shot and killed three Palestinians who were trying to plant a bomb.

Zeid Ra’ad al-Hussein, the United Nations High Commissioner for Human Rights, decried the “shocking killing of dozens” and the injury of hundreds by Israeli forces in the Palestinian areas.

Mr Zeid, a Jordanian prince who is leaving his post in August after a single term, said the international community needs to ensure justice for the victims. He added on the UN human rights office’s Twitter feed that perpetrators of “outrageous human rights violations” must be held to account.

US president Donald Trump said in a video message played at the new US embassy inauguration – which took place just 45 miles from the bloodshed on the Gaza border – that he remains committed to “facilitating a lasting peace agreement” between Israelis and Palestinians.

“A great day for Israel!” Mr Trump tweeted earlier.

However, yesterday’s steadily climbing death toll and wall-to-wall condemnation of the embassy move by the Arab world raised new doubts about Mr Trump’s ambitions to broker what he once said would be the Middle East “deal of the century”,

At least 52 Palestinians, including five minors, were killed, the Gaza health ministry said. A total of 1,204 were wounded by Israeli gunfire.

The ministry says this total includes 116 people who were in serious or critical condition.

At the embassy ceremony in Jerusalem, Mr Trump’s son-in-law and chief Middle East adviser Jared Kushner placed the blame on the Gaza protesters. He said: “As we have seen from the protests of the last month and even today those provoking violence are part of the problem and not part of the solution.”

Mr Kushner and Mr Trump’s daughter Ivanka led a high-powered American delegation that also included the treasury secretary and four Republican senators.

The new embassy will temporarily operate from an existing US consulate, until a decision has been made on a permanent location.

In Gaza, the Hamas-led protest was meant to be the biggest yet in a campaign against a decade-old blockade of the territory. The Israeli military estimated a turnout of about 40,000, saying this fell short of what Hamas had hoped for.

The march was also directed at the inauguration of the embassy.

Mr Trump added in his video address that the new embassy was opening “many, many years ahead of schedule”, adding that the US had “failed to acknowledge the obvious” for many years.

He said that he remains committed to “facilitating a lasting peace agreement”, and that he was “extending a hand of friendship to Israel, the Palestinians and to all of their neighbours”.

Moving the embassy from Tel Aviv to Jerusalem – a key Trump campaign promise – infuriated the Palestinians, who seek east Jerusalem as a future capital.

The clash is the biggest showdown in years between Israel’s military and Gaza’s Hamas rulers along the volatile border.